Coverslipping of the specimen slide represents the last working step in the preparation of specimens for subsequent microscopic investigation. Once the specimen has been prepared, it is arranged on the specimen slide and covered with a very thin coverslip. To protect the specimen, the coverslip is joined to the specimen slide using a coverslipping agent, usually a solvent-containing adhesive. Coverslipping can be accomplished both manually and with the use of automatically operating coverslipping machines.
DE 295 14 506 U1 discloses a coverslipping machine of this kind in which the specimen slides are arranged on a rotatably supported plate. A nozzle or hollow needle for applying the coverslipping agent is arranged in stationary fashion at one point on the machine. After application of the coverslipping agent, a coverslip is transported by means of a vacuum suction device, via a rotatably supported transport arm embodied in vertically adjustable fashion, to the specimen slide and placed thereon.
When the coverslipping machine is not being used, or during downtimes, the risk exists that the coverslipping agent may dry out in the hollow needle and thus clog it. Depending on the ambient temperature, drying of the coverslipping agent can occur after only a few minutes.
To eliminate this risk, coverslipping machines that have been described are provided with a separate container having solvent, into which the entire hollow-needle holder can be manually introduced. This obviously requires that a holding screw in the holding apparatus of the hollow needle holder must first have been loosened, so that the hollow needle holder is then pulled out of the holding apparatus and placed in the solvent container.
This arrangement reliably protects the hollow needle from drying out. The risk nevertheless still exists that introduction of the hollow needle into the solvent container will be overlooked or be performed only after a delay, and the coverslipping agent will have at least partly dried out so that uniform coverslipping agent application is not guaranteed.
Dried-out or partly dried-out coverslipping agent, however, inevitably results in damaged specimens, so that the laboriously prepared specimens become unusable.
An automatically operating coverslipping machine having a gripper system is known from the document “Leica DV5030, ‘The ideal glass coverslipper for histology and cytology,’ order no. 0707-2-1-101, 09/02, Sep. 2002.” The gripper system of the coverslipping machine is designed to take the specimen slides directly out of the transport baskets and deliver them to the coverslipping position. Here as well, the coverslipping agent is applied onto the specimen slide from a reservoir and a hollow needle (dispenser valve). For that purpose, the hollow needle is attached via a needle holder, in linearly movable fashion, to a guide arm.
In the event of an interruption or during work breaks, here again the needle holder having the hollow needle must be moved manually from the guide arm into a holding apparatus having a solvent container. The needle holder can is in this case easily be removed from the guide arm by way of orifices and guide rods and positioned in the holding apparatus of the solvent container. The problem nevertheless still exists that introduction of the hollow needle into the solvent container may be overlooked or performed only after a delay.
The Leica CV5030 unit presented here can be operated in standalone fashion or, with the Leica ST5020 Multistainer, as a combination staining and coverslipping system that operates completely automatically. It is of course necessary to ensure in this context that, if the “material flow” is not continuous, drying out of the hollow needle is ruled out.